Astronomers have discovered a warm Neptune-sized waterworld exoplanet that appears to have water and clouds. The planet is called HAT-P-26b.

This waterworld exoplanet is orbiting a dwarf-star approximately 437 light-years from Earth. Also, the planet is thought to have an atmosphere composed entirely of hydrogen and helium.

There has been a number of exoplanets that have been discovered. But little is known about their atmosphere especially for worlds smaller than Jupiter.

A study, led by Hannah Wakeford of NASA’s Goddard Space Flight Center in Maryland, affirms the exoplanet – HAT-P-26b, first discovered in 2010 – shows clear signs having water and clouds.

Observations were made from the NASA/ESA Hubble Space Telescope and NASA’s Spitzer Space Telescope, NASA researcher Dr. Hannah Wakeford. So, co-authors now report that the atmosphere of the ‘warm-Neptune’ HAT-P-26b — a planet that is similar in size to Solar System’s Neptune, but which orbits its host star more closely — has a very low metallicity, an indication of the how rich the planet is in all elements heavier than hydrogen and helium.

The atmosphere of the Neptune-mass exoplanet HAT-P-26b is unexpectedly primitive, composed primarily of hydrogen and helium. By combining observations from Hubble and Spitzer space telescopes, Wakeford et al determined that, unlike Neptune and Uranus, the exoplanet has relatively low metallicity. Image credit: NASA’s Goddard Space Flight Center.

Exoplanet HAT-P-26b. Image credit: NASA’s Goddard Space Flight Center.

The research team are hopeful their findings will contribute to better understanding of how atmospheric composition varies between exoplanets with different masses, and narrow down hypothetical models of planet formation.

The co-author Prof. David Sing, from the University of Exeter, UK, said: “This exciting new discovery shows that there is a lot more diversity in the atmospheres of these exoplanets than we have previously thought.”

Some statistics about the planet:

Discovered in: 2010
Mass: 0.0585218513042 (± 0.0071736462889) MJ
Semi-Major Axis: 0.0479 (± 0.0006) AU
Orbital Period: 4.234516 (± 1.5e-05) JD
Eccentricity: 0.124 (± 0.06)
Radius: 0.564725782364 (± 0.0517442265041) RJ
Inclination: 88.6 ( -0.9 +0.9 ) deg

As a result these new discoveries will help provide a better understanding of how atmospheric composition varies between exoplanets with different masses, and will help constrain models of planet formation.